1. Field of the Invention
The present invention relates to an active matrix circuit which is used for display with a liquid crystal, and other purposes.
2. Description of the Related Art
FIG. 6 schematically shows an example of a conventional active matrix display device. In a display area which is enclosed by a broken line in FIG. 6, transistors Tr as switching elements are arranged in matrix form such that a single transistor is provided for each matrix element. When attention is paid to an nth-row/mth-column element of the matrix, an image (data) signal line Y.sub.m is connected to the source of the transistor Tr and a gate (selection) signal line X.sub.n is connected to the gate electrode of the transistor Tr.
Attention is now paid to the transistor as the switching element, which performs data switching and drives a liquid crystal cell LC. An auxiliary capacitor C, which supplements the capacitance of the liquid crystal cell LC, is used to hold image data. The transistor Tr switches image data, i.e., a voltage, to be applied to the liquid crystal. The most serious problem in using a transistor as s switching element is leak current (or off-current) that flows in a state that no selection pulse is applied to the gate (non-selection state). If the leak current is large, the amount of charge stored in the pixel electrode and the auxiliary capacitor easily decreases, resulting in deterioration in display performance.